Yarn feeding device and method for yarn feeding

ABSTRACT

A yarn feeding device B of a weaving machine W comprising at least two yarn feeding appliances F 1 , F 2  delivering the same yarn quality in a weft mixing process. Each yarn feeding appliance comprises a variable speed control system C, a sensor arrangement  6  which supplies control signals for the size of the stored yarn supply, and t least one fault sensor Z 1 , Z 2 , by which means a fault signal X indicating a change in the weft mixing condition, e.g. a yarn break in the upstream from the stored yarn supply, can be emitted. A fault signal transmission link Q 1 , Q 2  is provided extending from each yarn feeding appliance to the speed control system C of each other yarn feeding appliance, and an over-regulating routine  6  is provided in each speed control system C, said routine enabling the speed to be increased before the change in the weft mixing condition, by means off the fault signal X, independently from the control signals of the sensor arrangement  6.

FIELD OF THE INVENTION

The invention relates to a yarn feeding device and to a method for feeding yarn.

BACKGROUND OF THE INVENTION

It is known e.g. from EP-A-0 195 469 to feed, by the appliances, the same yarn quality in a weft mixing process to a weaving machine. This measure results in a uniform fabric quality and reduces the operative load of each yarn feeding appliance because the yarn feeding appliance then will have a lower operating frequency and will run with reduced speed variations. An additional safety aspect is achieved leading to higher efficiency because the at least one further yarn feeding appliance at least temporarily may take over the feeding function for a disturbed yarn feeding appliance in the case of a yarn break occurring between the supply bobbin and the yarn supply in the yarn feeding appliance or in case of an emptied supply bobbin. It is then not necessary to switch off the weaving machine because of this disturbance. As soon as one yarn feeding appliance takes over the feeding function of another one the feeding frequency increases at the yarn feeding appliance which takes over. In the case that there are more than two yarn feeding appliances within the group for the same yarn quality, in some cases all further yarn feeding appliances will share the feeding function for the disturbed yarn feeding appliance. After the remedy of the disturbance the disturbed yarn feeding appliance again may take over its feeding function. This is a known and reliable operating principle.

Basically it is intended to form the yarn supply passage in a yarn feeding appliance just so big that the normal consumption by the weaving machine is covered without drastic speed variations occurring in the yarn feeding appliance. An unnecessarily large size of the yarn supply package could form the reason for other functional disturbances. Furthermore, yarn feeding appliances frequently operate with so-called yarn separation, i.e. the yarn windings in the stored yarn supply package on the storage body are separated from each other by intermediate distances such that the windings cannot disturbingly interfere with each other. Different yarn qualities need different yarn separations. When e.g. difficult yarn material is processed like polypropylene having a band cross-section or square cross-section in weaving machines having a big weaving width (more than 5 metres or more) so-called HD-yarn feeding appliances (heavy duty yarn feeding appliances) are employed for such yarn materials. HD-yarn feeding appliances comprise very powerful drive motors. This is the case in particular with projectile weaving machines or rapier weaving machines. Such a type of yarn material is complicated to process and requires a marked yarn separation on the storage body. Powerful drive motors are needed in order to allow strong accelerations and decelerations for all operating conditions, and in order to overcome, in some cases, the high and varying withdrawal resistance of the yarn from the supply bobbin. The yarn supply package stored on the storage body then is relatively small because of the marked yarn separation, i.e. just sufficient to cover the consumption during a weft mixing process with low feeding frequency for the yarn feeding appliance. The speed is controlled such that from the detected actual size of the yarn supply package control signals may be derived with the help of which the drive motor is accelerated or decelerated or driven with constant speed, or, in some cases, is stopped. A maximum speed is set as a threshold value. At least one disturbance sensor belongs to the conventional equipment of a yarn feeding appliance. The disturbance sensor generates a disturbance signal in case of a yarn break between the supply bobbin and the stored yarn supply package or in case of an emptied supply bobbin. This disturbance signal is transmitted to the control device of the weaving machine and may, in some cases, be utilised to switch off the weaving the control device of the weaving machine even such that the weaving machine controls the conventionally provided yarn selector such that the yarn selector ignores the yarn channel of the disturbed yarn feeding appliance and becomes adapted to the take over process of the feeding function by another yarn feeding appliance. The yarn feeding appliance which takes over or the yarn feeding appliances which take over, respectively, within the group will not be informed of this change in the weft mixing process when the disturbance signal is emitted because each yarn feeding appliance operates autonomously and only depending on the actual consumption. That is, the yarn feeding appliance which has to take over the feeding function will be informed only by the response of its sensor arrangement that the feeding frequency has increased. Since then the yarn supply package only may be relatively small, the drive motor of the yarn feeding appliances will in many cases not be apt to replenish the stored yarn supply package rapidly enough to cover the then higher individual consumption such that the yarn supply package may be totally consumed, that the yarn tension may increase, and that in the case of a projectile weaving machine the projectile will reach the opposite edge of the fabric too late. Then the weaving machine may have to be switched off even though the further operation of the weaving machine would be ensured per se by the yarn feeding appliance which takes over the feeding function from another feeding appliance. In other words, the yarn feeding appliance which takes over at least a part of the feeding function of a disturbed yarn feeding appliance is unable to adapt rapidly enough to the momentarily increasing individual consumption, because the yarn feeding device first accelerates autonomously when its sensor arrangement emits a control signal for an acceleration which control signal purely depends on consumption. Then the sufficient. Furthermore, such an extreme acceleration might tear the yarn. However, to form the stored yarn supply package beforehand large enough could in turn lead to other function disturbances.

In this case the point of origin is that the yarn feeding appliance which has to take over the feeding function of a disturbed yarn feeding appliance eventually does not feed at the point in time of the occurrence of the disturbance and basically runs with an accordingly adapted individual speed which first cannot cope with the upcoming higher feeding frequency.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a yarn feeding device of the type as mentioned and a method for feeding yarn by which functional disturbances can be avoided in the case of an increased feeding frequency for at least one yarn feeding appliance.

This object is achieved by the features of the attached claims.

The disturbance signal is transmitted in the yarn feeding device in real time via the signal transmission link to the variable speed control of the at least one further yarn feeding appliance of the group which continues to operate further on without disturbance. The disturbance signal is considered as an inducement to immediately raise the speed in the yarn feeding appliance which will take over, of course with the assumption that the speed is not already the maximum speed. By raising the speed the stored yarn supply package is enlarged immediately by the response to the disturbance signal such that the yarn quantity on the storage body suffices to cover even the higher demand without empting the yarn supply package when then the weft mixing process condition automatically changes to a higher individual feeding frequency due the disturbance signal. As a result, in the yarn channel of the yarn feeding appliance which takes over an operation disturbance as mentioned cannot result from the change of the weft mixing condition.

In accordance with the method the stored yarn supply package is preparatorily enlarged by an overruling speed increase initiated by the transmission of the disturbance signal in real time to the speed control of the yarn feeding appliance which takes over, such that the yarn feeding appliance is able to cope mainly with the complicated transition phase of a weft mixing process with individual low frequency to a higher feeding frequency without empting the yarn supply package. As soon as the transition phase has ended, the yarn feeding appliance anyhow is able without problems to feed with the higher feeding frequency since then the variable speed control is adapted to the new situation or has adjusted a higher speed level, respectively, when there was also a sufficiently large yarn supply package present in the transition phase.

The design of the yarn feeding appliance allowing to alternatingly transmit a disturbance signal in real time among the yarn feeding appliances within the group and to preparatorily increase the speed is of particular expedience if HD-yarn feeding appliances having powerful drive motors and marked yarn separation are provided, in particular in projectile weaving machines or rapier weaving machines of large weaving widths and in case of complicated yarn qualities. A large delicate yarn material e.g. could by polypropylene of band character or square character which may produce a relatively high withdrawal resistance from the supply bobbin. Such prerequisites could otherwise co-act in combination namely such that a yarn feeding appliance which has to take over the feeding function of another yarn feeding appliance gets empty during the transition phase and then gets into a disturbance condition itself.

In order to allow the employment of a simple control technique the disturbance sensors of the yarn feeding appliances within group are connected to a common interface. The interface is connected via a combination element to the weaving machine control device such that the weaving machine control device is set into a condition to e.g. adjust the yarn selector for the change of the weft mixing condition by means of the disturbance signal. The signal transmission link for the real time transmission of the respective disturbance signal of the yarn feeding appliance to at least one further yarn feeding appliance of the same group expediently branches off upstream of the combination element in the interface. In this fashion it can be achieved that the disturbance signal may be evaluated in both the control device of the weaving machine and the speed control of the respective yarn feeding appliance with the same intensity and clarity. Alternatively, the signal transmission link leading to the yarn feeding appliance speed control could extend through the control device of the weaving machine.

Autonomous yarn feeding appliances which do not need an information connection or a control connection, respectively, to the weaving machine for the feeding function but react automatically only to the yarn consumption, conventionally of the sensor arrangement are processed, and, in some cases, alternatively sensor signals representing counted wound on and counted wound off windings, and/or signals of a reference sensor. The speed control only acts in accordance with the information on the momentary size of the stored yarn supply package or of the tendency of the variation of the size of the stored yarn supply package, respectively, as provided from the sensor arrangement and the mentioned other sensor signals. For these reasons, the transmitted disturbance signal is considered in an overruling fashion, i.e. that then other control signals will not be considered. The overruling routine or over-regulating routine may be installed without problems by software in the speed control which conventionally is equipped with a programmable microprocessor.

The disturbance signals may be brought via opto-couplers into the interface or, respectively, may be combined in the interface on the way to the weaving machine control device via opto-couplers.

Since the yarn selector has to be informed on a change of the weft mixing conditions in order to then ignore the yarn channel of the disturbed yarn feeding appliance, or to block this yarn channel, it is expedient to either directly adjust the yarn selector in real time with the disturbance signal, or as usual via the control device of the weaving machine, respectively.

Each group may include even more than two yarn feeding appliances for the same yarn quality. Then different possibilities exist, either only one yarn feeding appliance within the group will be appointed to take over the yarn feeding function of the disturbed yarn feeding appliance, or all further yarn feeding appliances commonly share the feeding function which has to be taken over. Depending on the selected principle a signal transmission link is provided only towards one yarn feeding appliance, or signal transmission links are provided to all yarn feeding appliances within the group, respectively. Analogously in the case of a multi-colour weft mixing weaving process with several yarn qualities or colours and several groups of yarn feeding appliances, the same strategy is applied.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be explained with the help of the drawings wherein:

FIG. 1 schematically shows a yarn processing system having two yarn feeding appliances,

FIG. 2 shows details on the control sides, in the form of a block diagram, of the yarn processing system of FIG. 1, and

FIG. 3 shows two diagrams schematically illustrating the method by the speed of the yarn feeding appliances over the rotational angle of the weaving machine or the time, respectively.

DETAILED DESCRIPTION

The invention is explained on the basis of a projectile weaving machine W, e.g. having a weaving width of more than 5.0 m (FIG. 1), and of a yarn feeding device B consisting of a group of two heavy duty yarn feeding appliances F1, F2, including powerful drive motors M and operating with a relatively big yarn separation S, and which yarn feeding device B e.g. is feeding polypropylene material yarns Y1, Y2 (or a single yarn quality having band-shape or a square character) in a weft mixing process. The yarn feeding device B may contain more than two yarn feeding appliances, or even a further group intended for another yarn quality, respectively. The invention is also applicable to rapier weaving machines and, in some cases, to jet weaving machines. During a normal operation a weft mixing process is carried out, i.e. each yarn feeding appliance is feeding one weft yarn or consecutively is feeding several weft yarns before another yarn feeding appliance is feeding one yarn or subsequently is feeding several weft yarns. Furthermore, the yarn feeding device D is designed such that in case of a disturbance at a certain yarn feeding appliance like a yarn break upstream of the yarn supply package this yarn feeding appliance is taken out of operation, while its feeding function is taken over by at least one other yarn feeding appliance of the same group.

A yarn channel K1, K2 is associated to each yarn feeding appliance F1, F2 which yarn channel extends via a yarn selector D to an insertion device E of the weaving machine W. The yarn selector D transfers the yarn Y1 or Y2 of the currently operating yarn feeding appliance F1 or F2 to the insertion device E which inserts this yarn into the weaving shed of the weaving machine W. During this period of time the other yarn channel is blocked. The yarn selector D e.g. is controlled by a control device CU of the weaving machine.

The respective yarn feeding appliance F1, F2 releases the yarn Y1 (or Y2) from a supply bobbin 1 and winds the yarn with the help of a driven winding element 2 into a yarn supply package on a storage body 3. The yarn windings in the yarn supply package 8 are separated from each other in axial direction (yarn separation S). Then the yarn Y1 is withdrawn from the yarn supply package 8 e.g. by passing through a withdrawal brake 4 and a yarn guiding element 5.

A variable speed control C (e.g. equipped with a microprocessor) is provided for the drive motor M. The variable speed control C is connected with a sensor arrangement 6 for receiving control signals from the sensor arrangement 6, e.g. control signals of a minimum sensor Min and a maximum sensor Max for accelerating, decelerating, driving or stopping the drive motor M, respectively. The sensor arrangement 6 scans the size of the yarn supply package 8 on the storage body 3. Alternatively, a differently designed sensor arrangement may be employed which e.g. includes a not shown reference sensor and/or counting sensors for wound on and wound off windings. The variable speed control C is customised such that it forms a yarn supply package 8 on the storage body 3 adapted in the size (number of windings) to an average consumption such that the drive motor M only needs to rotate with an individual, largely uniform speed which is adapted to the average consumption during the weft mixing process and which is lower than the set maximum speed.

Additionally, at least one disturbance sensor Z1 or Z2 is provided for detecting e.g. whether the yarn is broken between the supply bobbin 1 and the yarn supply package 8 or within or at the exit of the winding element 2 or whether the supply bobbin 1 ran empty. In this case the disturbance sensor Z1 and/or Z2 will generate a disturbance signal which is transmitted to an interface G. The disturbance signal is indicated as a rectangular pulse X. The disturbance signal X which e.g. controls the yarn selector D such that the upcoming accordingly and that the disturbed yarn channel e.g. K1, is blocked.

The second yarn Y2 stems from a second yarn feeding appliance F having the same equipment and design.

A signal transmission link Q2 extends to the variable speed control C of the yarn feeding appliance F1. The disturbance signal X emitted from the other yarn feeding appliance F2 (from the disturbance sensor Z1′ and/or Z2′) can be transmitted on the signal transmission link Q2. An overruling routine U is provided in the variable speed control C. The overruling routine U automatically raises the speed of the drive motor M upon receipt of the disturbance signal X, in particular e.g. to the maximum speed.

By this speed increase the yarn winding package 8 is preparatorily enlarged such that the yarn supply package 8 will not be emptied during the subsequent transition to a higher feeding frequency of the yarn feeding appliance F1. After expiration of the transition phase (the time duration of the speed increase may be programmed or may be terminated by the next following response of the maximum sensor Max) the yarn feeding appliance F1 will be able, thanks to the enlarged yarn supply package 8, to adapt itself autonomously, automatically and without disturbance to the then higher feeding frequency.

A switch 7 is associated to the control device CU of the weaving machine W. The switch 7 is actuated when another disturbance should occur at the yarn feeding appliance F1 which disturbance could mean that the consumption of the weaving machine would no Longer be covered.

Both yarn feeding appliances F1, F2 of the yarn feeding device B in FIG. 2 are schematically incorporated into a block diagram showing the interface G. In the case of a disturbance the disturbance signal X of the respective disturbance sensor Z or Z′, respectively, of one of the yarn feeding appliances F1, F2 is transmitted to the interface G. A respective signal transmission link Q1 or Q2, respectively, branches off like a gate from the signal transmission link extending to a combination element 13 (including opto-couplers). The branched-off signal transmission link Q1 or Q2 extends to the variable speed control C of the respective other yarn feeding appliance F1 or F2 of the yarn feeding device B, respectively. A further signal transmission link 14 extends from the combination element 13 to the control device CU of the weaving machine.

The overruling routine U (over-regulation routine) of the speed control C may be installed e.g. by software. A circuit board is contained in the interface G at which circuit board different opto-couplers are mounted.

The method is described with the help of FIG. 3 based on the assumption that either a yarn break has occurred at the yarn feeding appliance F1 between the supply bobbin 1 and the yarn supply package 8, or that the supply bobbin 1 ran empty, and that a disturbance signal X was output.

The upper diagram in FIG. 3 illustrates that the drive motor M in the yarn feeding appliance F1 runs with a substantially uniform speed (curve 15) during the weft mixing process operation with the feeding frequency for PF1 (yarn Y1) which speed covers the consumption for this feeding frequency PF1. Within the pause between two respective feed cycles PF1 the other yarn feeding appliance F2 (lower diagram) carries out a respective feeding cycle PF2. The drive motor M of the second yarn feeding appliance F2 also runs with substantially uniform speed (curve 15) adapted to the consumption during the weft mixing process with the feeding frequency for PF2. The respective, substantially equal speeds are lower than the respectively set maximum speed Vmax.

Now a disturbance occurs in the yarn feeding appliance F2, e.g. a yarn break. The disturbance signal X is generated and transmitted to the variable speed control C of the yarn feeding appliance F1. The disturbance signal X effects now at the yarn feeding appliance F1 that the speed starting from the curve 15 immediately is raised with an e.g. predetermined speed increase increment R, in particular e.g. along a curve part 16 up to the maximum speed Vmax, or along the curve part 16′ finally swinging into (at 19) a higher speed level (curve part 17) which is adapted to the higher feeding frequency for PF1 plus PF2. In the case that the maximum sensor Max in the yarn feeding appliance F1 responds at the maximum speed Vmax, then the higher speed level (curve part 17) is reached such that the speed swings into this higher speed level. The adjustment of the speed and the speed increase increment R are carried out or set, respectively, depending on the design of the speed control and/or of the sensor arrangement. Then the larger size of the yarn supply package suffices in each case due to the speed increase increment R to allow the speed control C of the yarn feeding appliance F1 to easily adapt to the now higher feeding frequency for PF1 plus PF2 and to avoid specifically that the yarn supply package 8 runs empty during the transition phase of yarn feeding appliance F2 from only PF1-feeding cycles to PF1 plus PF2-feeding cycles. Without the application of the speed increase increment R by the transmitted disturbance signal X the speed would increase from the curve 15 only delayed to the disturbance, e.g. after response of the minimum sensor Min (approximately along the curve part 18) which could mean that the yarn supply package ran empty, because then the consumption increased by the added feeding cycles PF2 would be too high for the drive motor M.

Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention. 

1. Yarn feeding device of a weaving machine, comprising at least one group consisting of at least two yarn feeding appliances feeding the same yarn quality in a weft mixing process, each yarn feeding appliance including a variable speed control for a winding element, a sensor arrangement for the size of a yarn supply package on a storage body, which sensor arrangement delivers control signals and is connected to the speed control, and at least one disturbance sensor for outputting a disturbance signal indicating a change of the condition of the weft mixing process, wherein a real time disturbance signal transmission link is provided which extends from each yarn feeding appliance of the group to at least one further yarn feeding appliance of the group, and wherein an overruling routine is provided in each speed control by which overruling routine the speed of the winding element is increased in advance to the change of the condition of the weft mixing process by consideration of the disturbance signal independent from control signals originating from the sensor arrangement.
 2. Yarn feeding device as in claim 1, wherein the yarn feeding appliances of the group are equal high duty yarn feeding appliances having powerful drive motors and a large separation on the storage body, particularly for projectile weaving machines or rapier weaving machines having large weaving widths.
 3. Yarn feeding device as in claim 1, wherein the disturbance sensor of the yarn feeding appliances of the group are connected to a common interface, that the common interface is connected by a combination element with a weaving machine control device, and wherein each signal transmission link branches off upstream of the combination element to the speed control of at least the one further yarn feeding appliance of the group.
 4. Yarn feeding device as in claim 1 wherein the overruling routine is installed by software into the speed control.
 5. Yarn feeding device as in claim 3, wherein at least the combination element is an opto-coupler.
 6. Yarn feeding device as in claim 1, wherein a controlled yarn selector is provided at the weaving machine which releases only a respective yarn channel corresponding to the respective condition of the weft mixing process, and wherein the yarn channel of a disturbed yarn feeding appliance is blocked by the yarn selector either by means of the disturbance signal or via the control device of the weaving machine, respectively.
 7. Yarn feeding device as in claim 1, wherein the group includes more than two yarn feeding appliances, and wherein the disturbance signal of one yarn feeding appliance is transmitted to the speed control of only one further yarn feeding appliance or to the speed controls of all further yarn feeding appliances of the group, respectively.
 8. Method for feeding yarn into a weaving machine according to which method equal yarn qualities are fed in a weft mixing process by at least two yarn feeding appliances of at least one group, such that for the formation of a yarn supply package size on a storage body sufficiently large to cover the consumption the speed of each yarn feeding appliance is variably speed controlled under consideration of control signals derived from the yarn supply package size and such that a disturbance signal is generated in case of a change of the condition of the weft mixing process caused by a disturbance, wherein the disturbance signal of one yarn feeding appliance is transmitted in real time to a variable speed control of at least one further yarn feeding appliance of the group, and wherein the speed of the further yarn feeding appliance is raised by a speed increase increment at most to a predetermined maximum speed (Vmax) to preparatorily enlarge the yarn supply package size for the upcoming change of the condition of the weft mixing process. 